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BeagleBone Black I2C References

I’m planning on heavily using I2C for my CryptoCape. I’m still working through issues, but I wanted to capture some of my research in this post. As I’m currently experimenting, please treat this information as notes and not as definitive information. Feel free to post corrections in the comments and I’ll update the content.

The BeagleBone Black (BBB) has three I2C buses (thanks to Smith Winston providing most of this information at his BeagleBoard.org discussion post):

i2c0: Not exposed in the expansion headers

i2c1: pins P9 17,18 (and 24,26)

i2c2: pins P9 19,20 (and 21,22)

But, not all three buses are exported by default and more confusingly, under linux, the buses are named in the order they are enumerated which may have nothing to do with the physical names.

Enabling the Third I2C Bus

I received an answer on this post about how to see all three I2C buses. The following incantation seems to do the trick, but I’m not sure if interferes with any capes (the number after the bone_capemgr can change, so check your system):